Sheathed wire and terminal therefor.



W. K. KEARSLEY. SHEATHED WIRE AND TERMINALTHEREFOR. APPLICATION FILED H3. 1916.

1 ,2 1 3,88 1 Patented Jan. 30, 1917.

I 4! *AMMUNIQMMfiMfi HWWM' III IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII/IIIIIIIIA Inventor:

UNITED STATES PATENT OFFICE.

WILLIAM R. KEA sLEY, oE NEWARK, NEW JERsEY, ASSIGNOR 'ro COMPANY, A CORPORATION or NEW YORK.

GENERAL ELEo'rRm SHEATHED WIRE ANI) TERMINAL THEREFOR.

Specification of Lttters Patent.

Patented Jan. 30, 1917.

Application filed 119.123, 1916. Serial No. 99,306.

To all whom it may concern Be it'lmown that I, WILLIAM K. KEARS- LEY, a citizen of the United States, residing at Newark, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Sheathed Wires and Terminals Therefor, of which the following is a specification.

My invention relates to a compound or sheathed wire and a terminal therefor particularly applicable for electric heating and the like and to the method of manufacturing such wire. resistance core wiresurrounded by a metal sheath, the space between the core wire and the sheath being packed with a powdered insulating material. Sheathed wire of this character has hitherto been made, and a method of manufacture therefor is described in a patent to Chester N. Moore, No. 1,107,233, which was issued on August 11th, 1914, and to which reference may be had for fuller details of the method, of manufacture. One of the difficulties which has been encountered in sheathed wire of this character has been in the provision of a suitable terminal. The core of such wire is itself too slender and fragile to act as a terminal, and it has been proposed either to solder or 3 otherwise secure an enlarged terminal to the core wire, or to form, during the manufacture, an enlarged terminal which is integral with the core wire as shown in patent to Whitney, No. 1,093,512, which was issued on April 14th, 1914:. The first method is fairly expensive and the second method, that is in which an enlarged terminal is made integral "with the core wlre, a special machine in which rolls provided with a series of grooves are used, is usually required.

One of the objects of my invention is the provision of sheathed wire of this character formed with terminals of good conductivity, and which are easily formed durin the manufacture of the wire with an ordinary rolling machine.

Other objects of my invention will appear from the specification and will be particularly pointed out in the claims.

For a fuller understanding of my invention, reference may be had to the accompanying drawing, in which- Figure 1 is a longitudinal section of an ingot from which'the sheathed wire is prepared; Fig. 2 is a longitudinal; section" of The sheathed wire comprises a v be prepared. In pre sheathed wire made from the ingot of Fig. 1; Fig. 3 is a longitudinal section of an ingot from which a plurality of heating elements may be prepared, in accordance with a somewhat modified method; Fig. 4 is a longitudinal section of sheathed wire prepared from the ingot, shown in Fig. 3; Fig. 5 is a side view of one end of sheathed wire made in accordance with my invention; Fig. 6 is a longitudinal section showing how a flexible terminal may be secured to the end of the terminal made in accordance with my invention; and Fig. 7 shows a thimble or sleeve surrounding the end of the sheath and the joint formed between the flexible terminal and the sheathed wire terminal with a filling of cement or other insulating material.

Referring now to the drawings, and first to Fig. 1: 1 is a core wire of suitable material which, when the sheathed wire is to be used for heating device work, may be formed of an alloy of nickel and chromium or any other high resistance material. Metal sleeves or tubes 2 surround the ends of the core wire and the entire core wire is surrounded by a metal sheath 3 of sufficiently malleable and ductile material, such as mild steel, to be drawn down to the required diameter. The space between the core wire 1 ably stopped by washers 5. The ingot thus formed is then swaged or rolled down until the core wire acquires a diameter such as to give to the core wire the required resistance, the terminals and the sheath being reduced at the same time as shown in Fig. 2.. For this purpose the'sheathed wire may be passed through ordinary rolls and the sheath is kept uniform throughout in diameter. A section of the sheath and of the insulating material is then stripped from the end of the sheathed wire in order to expose the end. of the terminal tube.

In Fig. 3 I have shown an ingot from which a plurality of heating elements may paring the ingot, a plurality of metal sleeves or tubes 2 are secured on the core wire at points where the terminals are to be formed, and are usually uniformly spaced. The ingot is then reduced in accordance with the same method as previously described, and results in the sheathed wire shown in Fig. 4. In order to determine the points at which the sleeves or tubes are located in the reduced wire, I preferably pass an electric current through the core wire and by observing the hot and cold spots on the outer surface, the positions of the arious tubes may be determined. llt willof course be understood that the colder spots will appear opposite the sleeves, since the resistance of the core wire is very much less at these points. The sheathed wire is then cutthrough the middle of the various tubes and the terminals on the individual heating elements are formed in accordance with the same method as described in connection with Figs. land 2. -The method of making sheathed wire described in connection with Figs. 3 and 4 is particularly ap plicable where the wire is to be used in lengths of a few inches,-such as would be required for heating elements operating on a low voltage.

l. have, in Figs. 2 and 4-, applied the same reference numerals as in Figs. 1 and 3 respectively, with the exception that in Figs. 2 and 4: T have appended the character a to the corresponding reduced parts.

In F igs. 5, 6 and 1 T have shown a convenient method of attaching a flexible lead to the terminal formed in accordance with my invention. lln Fig. 5 is shown the end of a section of sheathed wire, and a terminal therefor made in accordance with my invention. To the end of this may be soldered or otherwisev secured, as at 6, a flexible lead 7. A sleeve 8 may then he slipped over the end of the sheath and brazed or otherwisesecured thereto. The sleeve also incloses the joint formed by the flexible lead 7, and the enlarged terminal 2 of the sheathed wire. The space within the sleeve 8 and surrounding the joint between the terminal 2 and lead ,7 may be filled with cement or any other desired insulating material 9.

Sheathed wire made in accordance with my invention is easily and quickly prepared, and l have found in practice that it is well adapted for certain classes of work, particularly where the sheathed wire is to be used as an open heater. It is obvious, of course, that the space between the terminal and the sheath, in the wire embodying my invention, is less than that between the body of the core wire and the sheath, and this would be objectionable for some classes of heating work, since, if the mainbody of the sheath were sufiiciently reduced to render it suitable for the desired purpose, the insulating space between the terminal and the sheath would be insufiicient. This, however, is of no importance where the sheathed wire is to he used as an open heater, since,

in this case, it is desirable to have a large radiating surface, and it is therefore possible to select the inclosing tube of the ingot of such a size relative to the core wire that an ample space will be provided between the terminal and the sheath in the finished wire.

In accordance with the provisions of the patent statutes, T have described the principle of operation of my invention, together with the apparatus which T now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means. i

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The method of making a resistance element'for electric heaters and the like, which consists in providing enlarged sections at the ends of a core wire, surrounding the core with a metal sheath, filling the space between the core and the sheath with powdered insulating material, and reducing the whole in cross section.

2. The method of making a resistance element for electric heaters and the like, which consists in surrounding a core wire provided with enlarged sections at the ends with a metal sheath, filling the space between the core and the sheath with powdered insu latin'g material, reducing the whole in cross section, and stripping the sheath and the insulation at the ends to expose the terminals.

3. The method of making a resistance element for electric heaters and the like, which consists in applying tubes to the ends of a core wire, surrounding the core with a metal sheath, filling the space between the core and the sheath with powdered insulating material, and reducing the whole in crosssection.

l. The method of making a resistance element for electric heaters and the like, which consists in applying tubes to the ends of a core wire, surrounding the core with a metal sheath, filling the space between the core and the sheath with powdered insulating mate rial, reducing the whole in cross section, and stripping the sheath and the insulation at the ends to expose the terminals.

\ 5.; The method of mal'ring a plurality of. resistance elements for electric heaters and the like, which consists in providing the core wire with enlarged sections, surround" ing the core with a metal sheath, filling the space between the two with powdered insulating material, reducing thewhole in cross section, and cutting the compound wire thus formed through the various enlarged sections.

6. The step in the method of determining the points at which the tubes are applied along a core wire surrounded by a metal sheath, between which and the core Wire is a filling of powdered insulating marial filling the space between the core wire ,terial which consists in passing a current and the sheath, and metaltubes surrounding 10 through the wire, and observing the hot the core wire at its ends and extending into and cold spots along the wire. the powdered material.

5 7. A compound vor sheathed wire com- In witness whereof, I have hereunto set prising a core wire surrounded by a metal my hand this 20th day of May, 1916. sheath substantially uniform in cross section throughout, powdered insulating mate- -WILLIAM K. KEARSLEY. 

